Process for removing contaminant from a surface and composition useful therefor

ABSTRACT

Particulate and metal ion contamination is removed from a surface, such as a semiconductor wafer containing copper damascene or dual damascene features, employing a fluoride-free aqueous composition comprising a dicarboxylic acid and/or salt thereof; and a hydroxycarboxylic acid and/or salt thereof or amine group containing acid.

TECHNICAL FIELD

[0001] The present invention relates to an acidic aqueous compositionthat is especially useful for removing particulate and metalliccontamination from a surface. The present invention is especially usefulfor removing particulate and metallic contaminants from structures suchas those used as interconnect structures in integrated circuit devicessuch as semiconductor wafers containing copper damascene and dualdamascene features. The structures treated according to the presentinvention include those that have been previously planarized by chemicalmechanical polishing.

BACKGROUND OF THE INVENTION

[0002] On VLSI and ULSI semiconductor chips, Al and alloys of Al areused for conventional chip interconnect/wiring material. However, morerecently copper and alloys of copper have been developed as chipinterconnect material. The use of copper and copper alloys results inimproved device performance when compared to Al and its alloys.

[0003] In the fabrication of semiconductor devices, the metallicinterconnect material or wiring such as the copper or its alloys istypically planarized after deposition.

[0004] Polishing slurries used for this planarization are typicallyaqueous suspensions comprised of a metal oxide abrasive (such asalumina), organic acids, surfactants, and a suitable oxidizing agent.This process is known as chemical-mechanical polishing (CMP). Theoxidizing agent works to enhance mechanical removal of material via acorrosion assisted process. Such oxidizing agents employed incommercially-available or proprietary slurries are typically inorganicmetal salts such as FeNO₃, or KIO₃, and also hydrogen peroxide, presentin significant concentrations. Other chemicals added to slurries toimprove dispersion or otherwise enhance performance often are organicacids (e.g. citric acid). Sodium, potassium, and iron salts and/orcompounds are frequently used in slurry formulations, and significantamounts of these metal ion impurities can remain on the wafer afterpolishing and post-polish cleaning.

[0005] Therefore, a tendency exists for various particulate contaminantsto remain on the polished surface. The particulate materials areextremely difficult to remove. This is particularly problematic sincethe removal must not adversely affect the polished surface.

[0006] Furthermore, since the polishing slurries typically contain anoxidizing agent, an oxide layer usually is present on the copper due tooxidization of the copper during the CMP process. This layer mayadversely affect the electrical characteristics of the device, and ispreferably removed. In fact, this layer may also contribute to thecontamination.

[0007] Accordingly, a need exists for a post chemical mechanicalpolishing cleaning chemistry that removes metallic and particulatecontamination. In addition, it is desired that the cleaning step removeany residual copper oxides and/or other non-desirable surface films,leaving a bare copper surface.

[0008] The problems of developing such a cleaning is further exacerbatedby the need to minimize etching of the copper as well as avoidingincreased surface roughness to any significant extent.

[0009] Moreover, compositions containing fluorides have been suggested.However, it has become desirable to provide fluoride-free compositionsdue to environmental considerations.

SUMMARY OF THE INVENTION

[0010] The present invention relates to an acidic aqueous solution thatis especially for cleaning metallic/metal ion contaminants andespecially metal and non-metal oxide particles remaining at or in thesurface of a semiconductor wafer following CMP.

[0011] The present invention is particularly useful for removingparticulate contaminants from copper. The present invention also removesany residual oxide layer found on the copper surface without etching orincreasing the surface roughness of the copper to any significantextent.

[0012] In particular, the present invention relates to a fluoride-freeaqueous composition comprising about 0.005 to about 16% by weight of atleast one dicarboxylic acid, salt thereof or mixture thereof,

[0013] about 0.003 to about 4% by weight of at least one hydroxycarboxylic acid, salt thereof or mixture thereof; or an aminegroup-containing acid and the remainder being substantially water, and

[0014] having a pH of about 1 to about 4.

[0015] A further aspect of the present invention is concerned with aprocess for removing particulate contaminants from a copper surfaceafter CMP planarization. In particular, the process comprises contactinga copper surface that has been planarized by CMP with one of theabove-disclosed aqueous compositions.

[0016] A still further aspect of the present invention relates to aprocess for fabricating semiconductor integrated circuits. The processcomprises forming circuits on the surface of a semiconductor wafer byphotolithographic process wherein the circuits comprise copper or copperalloy; planarizing the surface by chemical mechanical polishing; andremoving particulate and metallic (e.g.—metal ion) contaminants from thesurface by contacting with one of the above-disclosed aqueouscompositions.

[0017] Still other objects and advantages of the present invention willbecome readily apparent by those skilled in the art from the followingdetailed description, wherein it is shown and described only thepreferred embodiments of the invention, simply by way of illustration ofthe best mode contemplated of carrying out the invention. As will berealized the invention is capable of other and different embodiments,and its several details are capable of modifications in various obviousrespects, without departing from the invention. Accordingly, thedescription is to be regarded as illustrative in nature and not asrestrictive.

DESCRIPTION OF BEST AND VARIOUS MODES FOR CARRYING OUT INVENTION

[0018] A number of criteria must be considered to establish anacceptable wafer cleaning process. In particular, the ideal cleaningprocess should reduce particulate and metallic contaminants on the waferto the level present before the polishing step. Also, the cleaningprocess and chemistry must be compatible with the materials exposed onthe wafer surface after CMP. Furthermore, one should be able to performthe cleaning process safely using commercially available wafer orfabrication equipment. Moreover, it is desirable that the process berelatively inexpensive to implement. Furthermore, environmentalconsiderations make it desirable that the composition be fluoride-free.

[0019] The structures treated pursuant to the present invention aretypically semiconductor devices having copper interconnects (lines,plugs, vias, global and local interconnects) imbedded into a low kdielectric material such as silicon dioxide, which may also include acapping layer, such as silicon nitride as in low k dielectric/damasceneand dual damascene structures. The silicon dioxide is typically a highdensity plasma deposited silicon dioxide or TEOS(tetraethylorthosilicate).

[0020] The copper interconnects typically use either tantalum, tantalumnitride, or titanium or titanium nitride as a barrier or liner materialbetween the copper and the dielectric. As such, the post-CMP cleaningsolution is meant to clean up to four or more different materials,copper, the liner material, the dielectric or capping layer, as well asthe wafer backside, which is generally a thin layer of oxidized silicon.All these types of materials are exposed on the surface of thesemiconductor device during post-CMP cleaning. Accordingly, the cleaningcomposition must not adversely effect any of these materials to anundesired degree while still effectively removing the contaminants. Thisplaces considerable constraints upon developing a suitable composition.

[0021] The copper is planarized after deposition by chemical mechanicalpolishing typically employing an aqueous slurry comprising an abrasiveand an oxidizing agent. Such compositions are well known and need not bedescribed in any detail herein.

[0022] Examples of some chemical mechanical polishing slurries can befound in U.S. Pat. No. 5,527,423 and U.S. Pat. No. 5,693,239, and PCTpublication WO 97/43087, disclosures of which are incorporated herein byreference.

[0023] The structure is then contacted with a fluoride-free aqueouscomposition according to the present invention. The compositioncomprises at least one dicarboxylic acid and/or salt thereof; and atleast one hydroxycarboxylic acid and/or salt thereof; or an amine groupcontaining acid.

[0024] Use of the term “fluoride-free” herein refers to at leastsubstantially fluoride-free (e.g. containing no more than about 100 ppbof fluoride). Typical dicarboxylic acids include those having two to sixcarbon atoms, and include oxalic acid, malonic acid, succinic acid,glutaric acid, adipic acid, maleic acid and fumaric acid. The preferredacid is malonic acid. Suitable salts include the alkali metal, alkalineearth metal and ammonium salts. Preferably, a mixture comprising malonicacid and oxalic acid is employed.

[0025] Examples of hydroxycarboxylic acids includes malic acid, tartaricacid and citric acid.

[0026] The preferred hydroxycarboxylic acid is citric acid. Suitablesalts include alkali metal, alkaline earth metal and ammonium salts.

[0027] A preferred derivative is ammonium citrate. The amine-containingacid is preferably glycine.

[0028] In addition to water, preferably deionized water, the compositioncan include minor amounts (e.g. up to about 0.002% by weight of theactive portion) of a biocide. A typical biocide is Kathan. Kathancomprises:

[0029] 1.2% 5-chloro-2-methyl-4-isothiazolin-3-one

[0030] 0.4% 2-methyl-4-isothiazolin-3-one

[0031] 1.1% MgCl₂

[0032] 1.75% Mg(NO₃)₂

[0033] 0.16% copper nitrate trihydrate

[0034] water 95.85%.

[0035] The dicarboxylic acid and/or salt is typically present in amountsof about 0.005 to about 16 weight %, more typically about 0.1 to about 3weight % and preferably about 0.3 to about 0.5 weight %. When thepreferred mixture of oxalic acid and malonic acid is used, each one istypically present in amounts of about 0.003 to about 8 weight %, moretypically about 0.05 to about 1.5 weight % and preferably about 0.1 toabout 0.3 weight %.

[0036] The hydroxycarboxylic acid is typically present in thecomposition at amounts of about 0.003% to about 8% by weight, moretypically about 0.05 to about 1.5 weight % and preferably about 0.1% toabout 0.3% by weight.

[0037] When employed, the amino-group containing acid such as glycine istypically employed in amounts of about 0.003 to about 4% by weight, moretypically about 0.005 to about 1.5 weight % and preferably about 0.005to about 0.05% by weight.

[0038] In addition, the compositions of the present invention have a pHof about 1 to about 4 and preferably about 1 to about 3, a particularexample being about 2. The pH is typically measured using pH paper orsuitable pH reference electrode. It has been discovered according to thepresent invention that the pH is important in achieving objectives ofthe present invention. In particular, the compositions are capable ofremoving metallic and non-metallic particulate oxides, as well assilicon dioxide; metal ion contaminants such as K, Ca, Ti, Cr, Mn, Fe,Ni, Cu and Zn; various sulfur and chloride impurities adsorbed on thevarious surface materials present on the wafer. CuO is thermodynamicallyunstable within the pH range of the compositions of the presentinvention.

[0039] A further feature of the present invention is that thecomposition even in concentrated form is relatively stable. Forinstance, concentrates of the composition comprising about 0.1 to about16% by weight and preferably about 6% to about 10% by weight of thedicarboxylic acid, about 0.05% to about 8% by weight, and preferablyabout 3% to about 5% by weight of the dihydroxy carboxylic acid or aminoacid and the remainder being substantialy water can be provided andtransported to the end user, the user can then dilute it such as about a19:1 dilution by weight at the process tool for convenience and foreconomical reasons.

[0040] The composition can be used in a double sided brush scrubber toclean whole wafers following a copper CMP polishing step.

[0041] Moreover, such can be used in a megasonic bath or spray toolcleaning apparatus, or combination thereof.

[0042] The following non-limiting examples are presented to furtherillustrate the present invention.

EXAMPLE 1

[0043] A concentrate comprising about 160 grams of citric acid, about 80grams of malonic acid, about 160 grams of oxalic acid and about 10 gramsof Kathon™ biocide with about 3590 grams of ultra-high purity (UHP)water is prepared. The concentrate has pH of about 1.05 as measuredusing a calibrated antimony reference electrode or pH paper. Theconcentrate is then diluted 19:1 (by weight) with UHP H₂O to formulatean aqueous cleaning mixture, containing about 0.2 weight % of citricacid, about 0.1 weight % of malonic acid, about 0.2 weight % oxalicacid, about 0.0125 weight % Kathon™ biocide and about 99.5 weight % ofwater.

[0044] Wafers having copper lines embedded into silicon dioxide andlines with a liner material are first subjected to CMP employing anaqueous slurry comprising about 2% by weight alumina, about 3% by weightH₂O₂, with the remainder being water and minor additives. After the CMP,the wafers are contacted with the above aqueous cleaning mixture.

EXAMPLE 2

[0045] A concentrate comprising about 200 grams of oxalic acid, about 80grams of malonic acid, about 200 grams of glycine with about 3510 gramsof ultra-high purity (UHP) water is prepared. The concentrate has pH ofabout 2.15 as measured using a calibrated antimony reference electrodeor pH paper. The concentrate is then diluted 19:1 (by weight) with UHPH₂O to formulate an aqueous cleaning mixture containing about 0.25weight % of oxalic acid, about 0.1 weight % of malonic acid, about 0.25weight % glycine and about weight 99.4% of water.

[0046] Wafers having copper lines embedded into silicon dioxide andlines with a liner material are first subjected to CMP employing anaqueous slurry comprising about 2% by weight alumina, about 3% by weightH₂O₂, with the remainder being water and minor additives. After the CMP,the wafers are contacted with the above aqueous cleaning mixture.

EXAMPLE 3

[0047] In a series of cleaning experiments, a subset of the followingthree different wafer types are employed to characterize the cleaningperformance.

[0048] a) oxidized silicon substrates, with the oxide formed byplasma-enhanced chemical vapor deposition (PECVD) usingtetraethylorthosilicate (TEOS) precursor.

[0049] b) thermally oxidized silicon substrates (TOX).

[0050] c) silicon substrates covered with a thin film of TEOS oxide uponwhich is deposited 250 Å of Tantalum by physical vapor deposition (PVD)followed by 1 kÅ of PVD Cu.

[0051] d) Patterned wafer films consisting of etch trenches in TEOS,followed by deposition of 250 Å of Tantalum by physical vapor deposition(PVD) followed by 1 kÅ of PVD Cu and then 10 kÅ of electroplated Cu.

[0052] These wafer types as detailed above are then pre-processedaccording to either of three different approaches as typically done inpost-CMP clean characterization work.

[0053] a) No slurry processing with the wafer type being subjected tosubsequent cleaning only.

[0054] b) The wafer type receiving only a dip in the CMP slurry and thensubsequently cleaned.

[0055] c) The wafer type receiving polishing on a production quality CMPtool and then subsequently cleaned.

[0056] The preprocessed wafers as detailed above are then cleaned(post-processed) according to either of two different approaches astypically done in post-CMP clean characterization work.

[0057] a) cleaned using a double-sided brush scrubber

[0058] b) cleaned using the immersion technique in a megasonic bath.

[0059] The cleaned (post processed) wafers as detailed above are thencharacterized using accepted metrology tools as typically done inpost-CMP clean evaluation work including one or more of the following.

[0060] a) Particle performance using light scattering metrologyequipment

[0061] b) Elemental analysis using transmission X-ray fluorescence(TXRF) equipment

[0062] c) Elemental analysis using Drop Scan Etching (DSE) of thedissolved surface silicon dioxide coupled with inductively coupledplasma mass spectrometry (ICP-MS).

[0063] d) Static etch rate for copper and silicon dioxide via sheetresistance by 4-pt probe and oxide thickness via ellipsometry,respectively

[0064] e) Dynamic etch rate for copper and silicon dioxide via sheetresistance by 4-pt probe and oxide thickness via ellipsometry,respectively

[0065] f) Surface roughness of copper and oxide via atomic forcemicroscopy (AFM).

EXAMPLE 4

[0066] In a separate experiment, blanket TEOS films are processed inorder to quantify the particle-based and elemental-based cleaningperformance of the use-concentration chemistry depicted in example 1. Inall cases, TEOS films are first characterized by laser light scatteringon a Tencor 6420 and Tencor SP1, to determine the particle precountat >0.2 μm and at >0.16 μm, respectively. The wafers are either sentdirectly through the scrubber-based cleaner without any slurry or CMPexposure, with only a slurry dip in either commercially available Cu orTa slurry, or polished on an integrated CMP tool with the same slurryset. As seen in Table 1, the Tencor 6420 measurement tool indicates thatthe wafers improved their cleanliness in all cases. The slurry dip filmsare cleaned to the level of the wafer that is cleaned but without slurryexposure. The TEOS films which received CMP processing are alsosignificantly cleaner, but show slightly higher post counts, which maybe non-particulate defectivity introduced by the CMP process and thus,is not a clean chemistry issue. TABLE 1 Light point defect counts, preand post processing, using Tencor 6420 (>0.2 μm) and Tencor SP1 (>0.16μm) on wafers without slurry exposure, with a slurry dip and with actualCMP processing. Tencor SP1 Tencor 6420 LPDs Pre Post Delta Pre PostDelta Slurry Dip Al2O3 based-Cu Slurry 290 53 −243 38 12 −26 SiO2based-Ta Slurry 24 10 −14 10 3 −7 CMP Al2O3 based-Cu Slurry 348 452 10498 43 −55 SiO2 based-Ta Slurry 226 983 757 61 35 −26 No Slurry 433 45−388 174 9 −165 N/A

[0067] A subset of the processed TEOS films are subsequently analyzedfor surface elements on both wafer topside and backside using a RigakuModel 3276 Total X-ray Fluorescence Spectroscopy tool at 3 measurementsites per wafer. Table 2 displays the corresponding wafer averageresults and detection limits by element. Note that the Cl and S levelsare high and may either reflect a water quality issue at the experimentlocation or a genuine element issue. Metal element levels (Fe, Ni, Cu,Zn) for films which are slurry exposed are below 1 ell at/cm² in allcases. TABLE 2 Elemental analysis via TXRF on wafers processed withoutslurry exposure, with a slurry dip and with actual CMP processing,including smooth backside analysis. (All data is 1e10 at/cm2). TXRF FeNi Cu Zn Cl S Ca Slurry Dip Al2O3 based-Cu 9.9 6.5 1 3.4 818 175 5Slurry SiO2 based-Ta Slurry 9.6 6.3 2.2 1 1265 94 5 CMP Al2O3 based-Cu8.8 4.2 5.2 1.3 685 10 5 Slurry SiO2 based-Ta Slurry 6.1 2.3 3.7 1 499102 7.1 No Slurry 19.9 12.3 2.6 1 670 61 5 n/a Cleaned Upside Down Cu/TaSlurries 5.9 3.4 2.2 1 412 94 5 (Smooth Side TXRF) Det Limit 2 1 1 1 7.510 5 n/a

EXAMPLE 5

[0068] In a separate cleaning experiment, a single cassette containing24 wafers, each with a film stack of 1 kÅ PVD Cu/250 Å PVD Ta/TEOS/Si,is polished on a commercially available polishing platform with a twoslurry process. the first slurry is an alumina-based slurry for Curemoval while the second slurry is a silica-based slurry for Ta removal.The wafers are otherwise polished using traditional productionconsumables and process parameters to clear the metal from the TEOS. Thewafers are subsequently cleaned in a stand-alone, double-sided brushscrubber using the composition and dilution specified in Example 1. Eachwafer is characterized for post-CMP clean particles. Average postparticle counts (light point defects) as measured using a Tencor 6420with a detection threshold of about >0.2 μm is 8 adders with a standarddeviation of less than 4 adders showing both capability and stability ofperformance. Table 4 displays the corresponding data for each wafer. Thelow post-count magnitude reflects the excellent slurry and slurryby-product particulate cleaning capability of the clean chemistry. TABLE4 Light Point Defect Counts via Tencor 6420 Wafer# 1 2 3 4 5 6 7 8 9 1011 12 13 14 15 16 17 18 19 20 21 22 23 24 LPD > 0.2 μm 15 16 8 7 3 12 75 5 15 6 3 8 9 10 6 5 3 4 7 8 11 9 10

[0069] A 4 wafer subset of the processed TEOS films are subsequentlyanalyzed for surface elements on both topside and backside using aRigaku Model 3276 Total X-ray Fluorescence Spectroscopy tool at 3measurement sites per wafer. Table 5 displays the corresponding waferaverage results and detection limits by element. TABLE 5 Elementalanalysis via TXRF on 4 wafers (3 sites/wafer) processed without slurryexposure, with a slurry dip and with actual CMP processing, includingbackside analysis. (All data is 1e10 at/cm2) Fe Ni Cu Zn Cl S Ca Mean6.25 18.8 5.4 0 761 14.8 130 Std. Dev. 3.25 3.1 3.2 0 162 51.4 63.6 DetLimit 2 1 1 1 7.5 10 5

EXAMPLE 6

[0070] In a separate experiment, the static etch rate (SER) and dynamicetch rate (DER) of the use concentration clean chemistry specified inExample 1 is evaluated on Cu and TEOS films. For the static etch test,full 8″ wafers are placed in quantities of the use-concentrationchemistry (19 parts DI to 1 part concentrate) for 20 minutes, thensubsequently rinsed with UHP DI and dried. For the dynamic etch test,wafers are run through a double-sided brush scrubber at theuse-concentration for 20 minutes, rinsed and dried. The pre- andpost-process thickness are determined for the Cu and TEOS films by 4-ptprobe and ellipsometry, respectively. A low, but finite value of theetch rate is shown in call cases. The low etch rate magnitude of Cuprevents surface corrosion, grain, grain boundary and grain triple pointand film interface attack. It also minimizes associated surfaceroughness. The low but finite TEOS etch rates help in removing a thinand potentially element contaminated layer of TEOS. The pH of thecomposition is sufficiently low to destabilize surface copper oxide, yetminimizes the direct attack of Cu metal, with the intent to yield asclean and smooth a Cu surface as possible. TABLE 5 Etch Rate Data(Å/min) via 4-pt prove and ellipsometry Cu TEOS SER 4.5 3.0 DER 5.0 4.5

[0071] The polished and cleaned wafers are characterized with respect tosurface finish using an atomic force microscope. Both blanket Cu andpatterned films are polished using a silica-based slurry which polishesboth Cu, Ta and TEOS blanket films at approximately the same rate. Theblanket Cu film is partially polished using the silica-based slurry,buffed using UHP and H₂O and immediately cleaned using the compositionat use-concentration in a double-sided brush scrubber. The wafers arethen transferred to a Thermomicroscopes model M5 atomic forcemicroscope. Two locations on each wafer are measured. For the patternedfilms an 80 μm×80 μm bond pad is chosen. Within this bond pad the RMSaverage roughness over a 2 μm×2 μm square is determined. For the blanketfilms, a random location of two 2 μm×2 μm measurement sites is utilized.In both cases, very low RMS roughness is obtained, consistent with thelow static and dynamic etch rates measured in other experiments. Table 6displays the actual values determined. We note that these values arevery low, reflective of the low metal etch rate of the composition, andprovides for a smooth surface finish. TABLE 6 RMS Roughness (Angstroms)via M5 AFM Blanket Patterned Site 1 5.61 16.0 Site 2 7.23 17.1

EXAMPLE 7

[0072] In a separate example, a blanket thermally oxidized (TOX) siliconwafer is immersed in a megasonic tank filled with the composition fromExample 1 after dipping it into a custom slurry product which is basedupon an alumina abrasive and peroxide oxidizer system. The wafer issubsequently rinsed with UHP H₂O and dried. The TOX wafer ischaracterized using a Digital Nanoscope III atomic force microscope(AFM), Tencor Surfscan full-wafer light-point-defect detector both pre-and post-processing. Particle adders are −77 at >0.2 μm via the TencorSurfscan. Elemental analysis is performed using TXRF and indicated lowlevels, below the detection limits in almost all cases, with theexception of Fe, Ca and Zn which were close to the detection limit asshown in Table 7. The cleaning potential of the composition with respectto slurry abrasive particles and surface elemental contamination hasbeen clearly evidenced. TABLE 7 TXRF results K Ca Ti Cr Mn Fe Ni Cu ZnWafer 1 <10 6 <6 <1 <0.7 4.5 0.9 <0.6 1.9 Wafer 2 <10 8 8 <1 <0.9 6.40.8 <0.6 1.9

EXAMPLE 8

[0073] In a separate experiment, 25 blanket TEOS dummy wafers and 3 testTEOS wafers are processed in order to quantify the particle-based andelemental-based cleaning performance of the use-concentrationcomposition depicted in example 2. In all cases, test TEOS wafers arefirst characterized by laser light scattering on a Tencor 6420 todetermine the particle pre-count at >0.2 μm. The wafers are sentdirectly through the stand-alone double-sided scrubber-based cleaningtool without any slurry or CMP exposure. As seen in Table 8, the Tencor6420 measurement tool indicates that the wafers show low post-particlecounts in all cases.

[0074] Subsequent to the 28 TEOS films, test wafer are subjected to aslurry dip and subsequently sent through the stand-alone scrubber. Suchfilms show clean capability at the same level or better than thosewafers that are cleaned but did not have an initial slurry exposure asshown in Table 8. TABLE 8 Light point defect counts, pre and postprocessing, using Tencor 6420 (>0.2 μm) on wafers without slurryexposure and with a slurry. Tencor 6420 LPDs Pre Post Delta No Slurry 7166 −5 Clean Only No Slurry 27 55 28 Clean Only No Slurry 77 58 −19 CleanOnly Slurry Dip 35 41 6 SiO2 based - Ta Slurry

[0075] A subset of the processed TEOS films are subsequently analyzedfor surface elements on topside using a Rigaku Model 3276 Total X-rayFluorescence Spectroscopy tool at 3 measurement sites per wafer. Table 9displays the corresponding wafer average results and detection limits byelement. Note that the Cl level is high and may reflect a water qualityissue at the experiment location or a genuine element issue. Metalelement levels (Fe, Ni, Cu) for films which are slurry exposed to slurryare below 1.0 ell at/cm² in all cases. TABLE 9 Elemental analysis viaTXRF on wafers processed without slurry exposure and with a slurry dip.(All data is 1e10 at/cm2). TXRF Fe Ni Cu Cl S Ca Slurry Dip 9.6 6.3 2.21265 94 5 SiO2 based-Ta Slurry No Slurry Clean Only 5 16 4 742 10 60Det. Limit 2 1 1 7.5 10 5

EXAMPLE 9

[0076] In a separate cleaning experiment, two cassettes containing 30wafers total, each wafer with the film stack of 1 kÅ PVD Cu/250 Å PVDTa/TEOS/Si, are polished on a commercially available polishing platformwith a Ta slurry process. The slurry is a silica-based slurry for Taremoval, but also has an appreciable Cu polish rate. The wafers areotherwise polished using traditional production consumables and processparameters to clear the metal from the TEOS. The wafers are subsequentlycleaned in a stand-alone double-sided brush scrubber using thecomposition and dilution specified in Example 2. Each wafer ischaracterized for post-CMP clean particles. Average post particle counts(light point defects) as measured using a Tencor 6420 with a detectionthreshold of at >0.2 μm was 25.8 adders with a standard deviation of26.6 adders showing both capability and stability of performance. Note,wafer 5 is removed from the analysis due to an observed misprocess. Itis quite conceivable that other wafers are affected similarly, but sincethey were not analyzed by TXRF, it was not detected. Table 10 displaysthe corresponding data for each wafer. The low post count magnitudereflects the slurry and slurry by-product particulate cleaningcapability and stability of the composition of the invention andassociated process. TABLE 10 Light Point Defect Counts via Tencor 6420Waf.# 1 2 3 4  5 6 7 8 9 10 11 12 13 14 15 LPD @ > 0.2 um 11 15 16 10930k 15 10 7 11 6 19 17 19 34 38 Waf# 16 17 18 19 20 21 22 23 24 25 26 2728 29 30 LPD @ > 0.2 μm 44 39 30 28 23 18 21 30 120 4 8 21 8 11 5

[0077] A 2-wafer subset of the processed TEOS films are subsequentlyanalyzed for surface elements on wafer topside using a Rigaku Model 3276Total X-ray Fluorescence Spectroscopy tool at 3 measurement sites perwafer. Table 11 displays the corresponding wafer average results anddetection limits by element. TABLE 11 Elemental analysis via TXRF on 4wafers (3 sites/wafer) processed without slurry exposure, with a slurrydip and with actual CMP processing, including backside analysis. (Alldata is 1e10 at/cm2) Fe Ni Cu Zn Cl S Ca Mean 5.92 14.3 3.2 1 754 21.761.9 Std. Dev. 3.7 3.0 1.9 1 145 32.5 33.6 Det Limit 2 1 1 1 7.5 10 5

[0078] Note that the Cl levels are again high and reflect either a waterquality issue at the experiment location or a genuine element issue.Metal element levels (Fe, Ni, Cu, Zn) for these slurry-exposed films arebelow 2 e11 at/cm² in all cases and reflect the elemental cleaningcapability of the compositions of the present invention.

[0079] The foregoing description of the invention illustrates anddescribes the present invention. Additionally, the disclosure shows anddescribes only the preferred embodiments of the invention but, asmentioned above, it is to be understood that the invention is capable ofuse in various other combinations, modifications, and environments andis capable of changes or modifications within the scope of the inventiveconcept as expressed herein, commensurate with the above teachingsand/or the skill or knowledge of the relevant art. The embodimentsdescribed hereinabove are further intended to explain best modes knownof practicing the invention and to enable others skilled in the art toutilize the invention in such, or other, embodiments and with thevarious modifications required by the particular applications or uses ofthe invention. Accordingly, the description is not intended to limit theinvention to the form disclosed herein. Also, it is intended that theappended claims be construed to include alternative embodiments.

What is claimed is:
 1. A fluoride-free aqueous composition comprisingabout 0.005 to about 16% by weight of at least one dicarboxylic acid,salt thereof or mixture thereof; about 0.003 to about 4% by weight of atleast one hydroxy carboxylic acid, salt thereof or mixture thereof; andthe remainder being substantially water; and having a pH of about 1 toabout
 4. 2. The composition of claim 1 wherein the dicarboxylic acid orsalt thereof has two to six carbon atoms.
 3. The composition of claim 1wherein the dicarboxylic @ acid is selected from the group consisting ofoxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid,maleic acid and fumaric acid.
 4. The composition of claim 1 wherein thedicarboxylic acid comprises a mixture of malonic acid and oxalic acid.5. The composition of claim 4 wherein the amount of said malonic acid isabout 0.003 to about 8% by weight and the amount of said oxalic acid isabout 0.003 to about 8% by weight.
 6. The composition of claim 1 whereinthe hydroxy carboxylic acid is selected from the group consisting ofmalic acid, tartaric acid and citric acid.
 7. The composition of claim 1which comprises citric acid or ammonium citrate.
 8. The composition ofclaim 1 which comprises citric acid.
 9. The composition of claim 1 whichcomprises ammonium citrate.
 10. A fluoride-free aqueous compositioncomprising about 0.003 to about 8% by weight of malonic acid; about0.003 to about 8% by weight of oxalic acid; about 0.003 to about 4% byweight of citric acid; and the remainder being substantially water; andhaving a pH of about 1 to about
 4. 11. The composition of claim 10comprising about 0.2% by weight of citric acid; about 0.1% by weight ofmalonic acid and about 0.2% by weight of oxalic acid.
 12. Thecomposition of claim 10 which further comprises a biocide.
 13. Thecomposition of claim 12 wherein the amount of said biocide is up toabout 0.002% by weight.
 14. The composition of claim 12 wherein theamount of said biocide is about 0.00005% by weight.
 15. The compositionof claim 10 wherein the pH is up to about
 2. 16. A fluoride-free aqueouscomposition comprising about 0.005 to about 16% by weight of at leastone dicarboxylic acid, salt thereof or mixture thereof; about 0.003 toabout 4% by weight of at least one amine group containing acid, saltthereof or mixture thereof; and the remainder being substantially water;and having a pH of about 1 to about
 4. 17. The composition of claim 16wherein the dicarboxylic acid or salt thereof has two to six carbonatoms.
 18. The composition of claim 16 wherein the dicarboxylic acid isselected from the group consisting of oxalic acid, malonic acid,succinic acid, glutaric acid, adipic acid, maleic acid and fumaric acid.19. The composition of claim 16 wherein the dicarboxylic acid comprisesa mixture of malonic acid and oxalic acid.
 20. The composition of claim16 wherein said at least one amine group containing acid is glycine. 21.A fluoride-free aqueous composition comprising about 0.003 to about 8%by weight of malonic acid; about 0.003 to about 8% by weight of oxalicacid; about 0.003 to about 4% by weight of glycine; and the remainderbeing substantially water; and having a pH of about 1 to about
 4. 22.The composition of claim 21 comprising about 0.25% by wieght of glycine;about 0.1% by weight of malonic acid and about 5% by weight of oxalicacid.
 23. The composition of claim 21 which further comprises a biocide.24. The composition of claim 23 wherein the amount of said biocide is upto about 0.002% by weight.
 25. The composition of claim 23 wherein theamount of said biocide is about 0.00005% by weight.
 26. The compositionof claim 21 wherein the pH is up to about
 2. 27. A process for removingparticulate contaminants from a copper surface after CMP planarizationwhich comprisess contacting a copper surface that has been planarized byCMP with the aqueous composition of claim
 1. 28. A process for removingparticulate contaminants from a copper surface after CMP planarizationwhich comprisess contacting a copper surface that has been planarized byCMP with the aqueous composition of claim
 16. 39. A process forfabricating semiconductor integrated circuits comprising: formingcircuits on the surface of a semiconductor wafer by photolithographicprocess wherein the circuits comprise copper or copper alloy;planarizing the surface by chemical mechanical polishing; and removingthe particulate contaminants from the surface by contacting with theaqueous composition of claim
 1. 30. The process of claim 29 wherein thecopper or copper alloy is imbedded into a dielectric material andwherein a barrier layer is present between the dielectric material andcopper or copper alloys.
 31. The process of claim 30 wherein thedielectric is silicon dioxide and the barrier layer is at least onematerial selected from the group consisting of tantalum, titanium andnitrides thereof.
 32. A process for fabricating semiconductor integratedcircuits comprising: forming circuits on the surface of a semiconductorwafer by photolithographic process wherein the circuits comprise copperor copper alloy; planarizing the surface by chemical mechanicalpolishing; and removing the particulate contaminants from the surface bycontacting with the aqueous composition of claim
 16. 33. The process ofclaim 32 wherein the copper or copper alloy is imbedded into adielectric material and wherein a barrier layer is present between thedielectric material and copper or copper alloys.
 34. The process ofclaim 33 wherein the dielectric is silicon dioxide and the barrier layeris at least one material selected from the group consisting of tantalum,titanium and nitrides thereof.